Pyrazoles with a “click” 4-[N-(4-fluorobutyl)-1,2,3-triazole] substituent in position 3 are nanomolar CB1 receptor ligands

Abstract Replacement of the 3-carbonylaminopiperidine substitutent with a “click” 4-[ N -(4-fluorobutyl)-(1,2,3-triazolyl)] group in Rimonabant-type pyrazoles produced a novel class of nanomolar CB 1 receptor ligands. Molecule 1d is the most promising lead with a K i  = 23 nM for CB 1 , which is very close to that displayed by Rimonabant (SR141716), and fairly good CB 1 /CB 2 selectivity ( K i CB 2 / K i CB 1  = 35.5), thus representing a promising candidate for [ 18 F]radiolabeling and PET Imaging studies of the CB 1 receptor.